The U.S. Department of State requires passport photos to have been taken within six months of applying for a passport to ensure they show the current appearance of the applicant. Since babies may change appearance rapidly, it's best to have the most recent photo possible of your baby. When having a passport photo taken, your baby must be looking directly at the camera with both eyes open. The entire face including hairline and both ears must be visible. Your baby must be dressed in everyday attire without a hat, pacifier or pair of sunglasses obstructing the view of his face.
U.S. passport photos must have a white or off-white background. Take care to ensure there are no shadows in the background or on the baby for the photos. Parents' hands are also prohibited from being in the background. For a baby unable to sit upright, lay a white poster board or sheet down and lay the baby on top. A sheet can also be used to cover a car seat (including all buckles, straps, etc.) and the baby set inside if a photo without shadows can be obtained. For babies who can sit upright, sit them in front of white backgrounds, using sheets, poster boards or large sheets of paper. To avoid your child casting a shadow on the background, place a lamp behind him to illuminate the background.
You must provide two identical photos when applying for your baby's passport. Final photos should be 2-by-3 inches in size. The height of your baby's head in the photo must be between 1 inch and 1 and 3/8 inches from bottom of chin to top of head. The photos should be clear, with a continuous tone. According to the U.S. Department of State, photos must be "printed on thin, photo-quality paper." Take care to avoid smudges, lines or dots in the photos as these may result in the photos being rejected.